@makemineatriple765
Asian students are under-represented at Oxford relative to the share of top grades they achieve but the acceptance rate is on par with other groups so like I said its because they under-apply to the university relative to others. There isn't a different standard for them due to race.
Every ethnicity of student at Oxford has to achieve the required grades to get in though some are slightly over or slightly under represented at a population level relative to the proportion the A-level grades achieved.
So for instance, 5% of total top grades (across everyone) may be achieved by ethnicity A, but lets say lots of students from ethnicity A apply to Oxford and so they make up 7% of applicants with the required grades and offers (they disproportionately apply to Oxford).
Another group might represent 10% of total top grades but only represent 8% of the applicants and offers. They under-apply relative to their share of the top grades and this could be for any number of reasons.
Anyway, as concerns Oxbridge, there isn't a major issue one way or another. They could do more outreach to Asian students to encourage more applicants but the under representation is I think just a few percentage points so its nothing hugely significant.
Overall BAME students earn more of the top grades than their share of the general population but they are also make up a larger share of Oxford admissions.
The main significant disparities between those earning top grades and admissions is state vs private and north and south regionally.